Several studies have demonstrated improved outcomes when intensive care units (ICUs) are staffed by intensivists. Data supporting the benefits of 24-hour intensivist staffing have been inconsistent, with most studies hailing from single centers. In the May issue of The New England Journal of Medicine, researchers from the University of Pittsburgh School of Medicine in Pennsylvania retrospectively examined the relationship between nighttime intensivist physician staffing and mortality among ICU patients in a multicenter study involving 34 hospitals using the Acute Physiology and Chronic Health Evaluation (APACHE) clinical information system.

Data from 49 ICUs representing 65,752 patients in 25 hospitals were analyzed. High-intensity staffing was defined as the presence of an intensivist in the ICU during daytime hours with mandatory consultation. Low-intensity staffing was defined as optional intensivist consultation during daytime hours. Multivariable regression models were constructed, including general estimating equations to control for ICU-level patient clustering. Spline and interaction terms were evaluated in these models as indicated. A sensitivity analysis was performed to determine the impact of resident coverage at night in the absence of an intensivist. A second retrospective cohort in Pennsylvania hospitals was evaluated to verify the results from the multicenter analysis.

Nighttime staffing was associated with reduced in-hospital mortality only in low-intensity daytime ICUs (odds ratio [OR], lower risk of death 0.62; 95% confidence interval [CI], 0.39-0.97; P=0.04), but not in high-intensity daytime ICUs (OR 1.08; 95% CI 0.63-1.84; P=0.78). The same findings were confirmed in the secondary Pennsylvania cohort. In a sensitivity analysis that examined the role of residents for nighttime coverage, in-hospital mortality was found to be reduced in both low-intensity and high-intensity daytime ICUs. The authors concluded that blanket coverage of ICUs with 24-hour intensivist staffing might not be justified when mortality alone is considered.

Only the outcome of mortality was evaluated in this study, and the effect of 24-hour intensivist staffing on other outcomes – such as reducing length of stay, ventilator days and improving functional outcomes – remains unknown. The sample population used for this study tended to be comprised of larger hospitals with academic affiliations, though the validation cohort in Pennsylvania replicated the findings from the primary analysis. With regional shortages of intensivists, these data provide additional evidence that must be considered before 24-hour intensivist coverage is endorsed and mandated by regulatory agencies. Additional studies examining the potential benefits of intensivist staffing beyond measures of mortality also are warranted.